IL-17A Recruits Rab35 to IL-17R to Mediate PKCα-Dependent Stress Fiber Formation and Airway Smooth Muscle Contractility

Integrative Roles of Pro-Inflammatory Cytokines on Airway Smooth Muscle Structure and Function in Asthma

Asthma has become more appreciated for its heterogeneity with studies identifying type 2 and non-type 2 phenotypes/endotypes that ultimately lead to airflow obstruction, airway hyperresponsiveness, and remodeling. The pro-inflammatory environment in asthma influences airway smooth muscle (ASM) structure and function. ASM has a vast repertoire of inflammatory receptors that, upon activation, contribute to prominent features in asthma, notably immune cell recruitment and activation, hypercontractility, proliferation, migration, and extracellular matrix protein deposition. These pro-inflammatory responses in ASM can be mediated by both type 2 (e.g., IL-4, IL-13, and TSLP) and non-type 2 (e.g., TNFα, IFNγ, IL-17A, and TGFβ) cytokines, highlighting roles for ASM in type 2 and non-type 2 asthma phenotypes/endotypes. In recent years, there has been considerable advances in understanding how pro-inflammatory cytokines promote ASM dysfunction and impair responsiveness to asthma therapy, corticosteroids and long-acting β2-adrenergic receptor agonists (LABAs). Transcriptomic analyses on human ASM cells and tissues have expanded our knowledge in this area but have also raised new questions regarding ASM and its role in asthma. In this review, we discuss how pro-inflammatory cytokines, corticosteroids, and LABAs affect ASM structure and function, with particular focus on changes in gene expression and transcriptional programs in type 2 and non-type 2 asthma.

Dual blockade of interleukin-17A and interleukin-17F as a therapeutic strategy for liver fibrosis: Investigating the potential effect and mechanism of brodalumab

Liver fibrosis is a terminal manifestation of various chronic liver diseases. There are no drugs that can reverse the condition. Recently, the importance of interleukin-17 (IL17) in the pathophysiology has been revealed and has attracted attention as a therapeutic target. We aimed to reveal the roles of IL17A and IL17F in liver fibrosis, and to validate the potential of their dual blockade as therapeutic strategy. First, we retrospectively reviewed the longitudinal change of FIB-4 index, a clinical indicator of liver fibrosis, among psoriasis patients treated by brodalumab, which blocks IL17 receptor A (IL17RA). Next, we examined anti-fibrotic efficacy of anti-IL17RA antibody (Ab) in two murine liver fibrosis models by histopathological investigation and real-time reverse transcription polymerase chain reaction (RT-PCR). Finally, we analyzed the effect of IL17A and IL17F upon human hepatic stellate cells with RNA sequencing, real-time RT-PCR, western blotting, chromatin immunoprecipitation, and flow cytometry. Clinical data showed that FIB-4 index significantly decreased among psoriasis patients treated by brodalumab. In vivo studies additionally demonstrated that anti-IL17RA Ab ameliorates liver fibrosis induced by tetrachloride and methionine-choline deficient diet. Furthermore, in vitro experiments revealed that both IL17A and IL17F enhance cell-surface expression of transforming growth factor-β receptor II and promote pro-fibrotic gene expression via the JUN pathway in human hepatic stellate cells. Our insights suggest that IL17A and IL17F share their pro-fibrotic function in the context of liver fibrosis, and moreover, dual blockade of IL17A and IL17F by anti-IL17RA Ab would be a promising strategy for the management of liver fibrosis.

Lymphotoxin beta receptor signaling directly controls airway smooth muscle deregulation and asthmatic lung dysfunction

BACKGROUND

Dysregulation of airway smooth muscle cells (ASM) is central to the severity of asthma. Which molecules dominantly control ASM in asthma is unclear. High levels of the cytokine LIGHT (aka TNFSF14) have been linked to asthma severity and lower baseline predicted FEV1 percentage, implying that signals through its receptors might directly control ASM dysfunction.

OBJECTIVE

Our study sought to determine whether signaling via lymphotoxin beta receptor (LTβR) or herpesvirus entry mediator from LIGHT dominantly drives ASM hyperreactivity induced by allergen.

METHODS

Conditional knockout mice deficient for LTβR or herpesvirus entry mediator in smooth muscle cells were used to determine their role in ASM deregulation and airway hyperresponsiveness (AHR) in vivo. Human ASM were used to study signals induced by LTβR.

RESULTS

LTβR was strongly expressed in ASM from normal and asthmatic subjects compared to several other receptors implicated in smooth muscle deregulation. Correspondingly, conditional deletion of LTβR only in smooth muscle cells in smMHCCreLTβRfl/fl mice minimized changes in their numbers and mass as well as AHR induced by house dust mite allergen in a model of severe asthma. Intratracheal LIGHT administration independently induced ASM hypertrophy and AHR in vivo dependent on direct LTβR signals to ASM. LIGHT promoted contractility, hypertrophy, and hyperplasia of human ASM in vitro. Distinguishing LTβR from the receptors for IL-13, TNF, and IL-17, which have also been implicated in smooth muscle dysregulation, LIGHT promoted NF-κB-inducing kinase-dependent noncanonical nuclear factor kappa-light-chain enhancer of activated B cells in ASM in vitro, leading to sustained accumulation of F-actin, phosphorylation of myosin light chain kinase, and contractile activity.

CONCLUSIONS

LTβR signals directly and dominantly drive airway smooth muscle hyperresponsiveness relevant for pathogenesis of airway remodeling in severe asthma.

Neutrophil breaching of the blood vessel pericyte layer during diapedesis requires mast cell-derived IL-17A

Neutrophil diapedesis is an immediate step following infections and injury and is driven by complex interactions between leukocytes and various components of the blood vessel wall. Here, we show that perivascular mast cells (MC) are key regulators of neutrophil behaviour within the sub-endothelial space of inflamed venules. Using confocal intravital microscopy, we observe directed abluminal neutrophil motility along pericyte processes towards perivascular MCs, a response that created neutrophil extravasation hotspots. Conversely, MC-deficiency and pharmacological or genetic blockade of IL-17A leads to impaired neutrophil sub-endothelial migration and breaching of the pericyte layer. Mechanistically, identifying MCs as a significant cellular source of IL-17A, we establish that MC-derived IL-17A regulates the enrichment of key effector molecules ICAM-1 and CXCL1 in nearby pericytes. Collectively, we identify a novel MC-IL-17A-pericyte axis as modulator of the final steps of neutrophil diapedesis, with potential translational implications for inflammatory disorders driven by increased neutrophil diapedesis.

Mechanisms of Corticosteroid Resistance in Type 17 Asthma

IL-17A plays an important role in the pathogenesis of asthma, particularly the neutrophilic corticosteroid (CS)-resistant subtype of asthma. Clinical studies suggest that a subset of asthma patients, i.e., Th17/IL-17A-mediated (type 17) CS-resistant neutrophilic asthma, may improve with Th17/IL-17A pathway blockade. However, little is known about the mechanisms underlying type 17 asthma and CS response. In this article, we show that blood levels of lipocalin-2 (LCN2) and serum amyloid A (SAA) levels are positively correlated with IL-17A levels and are not inhibited by high-dose CS usage in asthma patients. In airway cell culture systems, IL-17A induces these two secreted proteins, and their induction is enhanced by CS. Furthermore, plasma LCN2 and SAA levels are increased in mice on a preclinical type 17 asthma model, correlated to IL-17A levels, and are not reduced by glucocorticoid (GC). In the mechanistic studies, we identify CEBPB as the critical transcription factor responsible for the synergistic induction of LCN2 and SAA by IL-17A and GC. IL-17A and GC collaboratively regulate CEBPB at both transcriptional and posttranscriptional levels. The posttranscriptional regulation of CEBPB is mediated in part by Act1, the adaptor and RNA binding protein in IL-17A signaling, which directly binds CEBPB mRNA and inhibits its degradation. Overall, our findings suggest that blood LCN2 and SAA levels may be associated with a type 17 asthma subtype and provide insight into the molecular mechanism of the IL-17A-Act1/CEBPB axis on these CS-resistant genes.

IL-17A promotes Psoriasis-associated Keratinocyte Proliferation via ACT1-depedent Activation of YAP-AREG Axis

Psoriasis is a recurrent inflammatory skin disorder characterized by epidermal hyperplasia which is primarily driven by interleukin (IL)-17A. The Hippo-YAP signaling pathway plays a vital role in cell survival and tissue growth, and its target gene, AREG, has been reported to promote the development of psoriasis. However, whether IL-17A promotes keratinocyte proliferation via regulating Hippo-YAP signaling has not been explored. Here, we show that the YAP-AREG pathway is activated in human psoriatic skin and is suppressed by IL-17A antagonist secukinumab and that IMQ and IL-17A administration activates the YAP-AREG axis in mice epidermis. In vitro studies using HaCaT and NHEK cells suggest that IL-17A enhances AREG expression and keratinocyte proliferation by activating Hippo-YAP signaling. Mechanistically, IL-17A stimulates the recruitment of MST1 to ACT1 in keratinocytes, which leads to reduced MST1-LATS1 interaction and YAP dephosphorylation. Together, our findings reveal a previously unknown mechanism in which IL-17A promotes keratinocyte proliferation in psoriasis, namely through activating YAP-AREG signaling.

RNA-Binding Protein HuR Promotes Airway Inflammation in a House Dust Mite-Induced Allergic Asthma Model

Mounting evidence indicates that interleukin 17 (IL-17) is critically involved in the pathogenesis of severe asthma. We have previously reported that upon IL-17 stimulation, Act1, an IL-17-receptor-complex adaptor, directly binds to its target mRNAs and utilizes other proteins, such as HuR, to upregulate mRNA stability and translation. HuR mRNA targets include multiple asthma-related genes. In this study, we have used house dust mite (HDM), a natural allergen, to test the role of HuR in the pathogenesis of allergic asthma. We found that HuR deletion in airway epithelium diminished HDM-induced lung inflammation, including neutrophil and eosinophil infiltration. While Th2 cytokines were not altered, the production of CXCL1, CXCL5 and CCL11 chemokines was significantly diminished. Airway smooth muscle (ASM) cells contribute to the pathogenesis of allergic asthma by orchestrating inflammatory and remodeling responses. We found that IL-17 treatment of ASM cells induced translocation of HuR from nucleus to cytoplasm, where it bound directly to Cxcl1 and Ccl11 mRNA. Deletion of HuR in ASM cells decreased their proliferation as well as CXCL1 and CCL11 production in response to IL-17. Taken together, our findings demonstrate the importance of HuR-mediated regulation of gene expression to the pathogenesis of allergic asthma, in both airway epithelial and ASM cells.

Fascin-1: Updated biological functions and therapeutic implications in cancer biology

Filopodia are cellular protrusions that respond to a variety of stimuli. Filopodia are formed when actin is bound to the protein Fascin, which may play a crucial role in cellular interactions and motility during cancer metastasis. Significantly, the noncanonical features of Fascin-1 are gradually being clarified, including the related molecular network contributing to metabolic reprogramming, chemotherapy resistance, stemness ac-tivity, and tumor microenvironment events. However, the relationship between biological characteristics and pathological features to identify effective therapeutic strategies needs to be studied further. The pur-pose of this review article is to provide a broad overview of the latest molecular networks and multiomics research regarding fascins and cancer. It also highlights their direct and indirect effects on available cancer treatments. With this multidisciplinary approach, researchers and clinicians can gain the most relevant in-formation on the function of fascins in cancer progression, which may facilitate clinical applications in the future.

Comparative Transcriptomics of IBD Patients Indicates Induction of Type 2 Immunity Irrespective of the Disease Ideotype

Inflammatory cytokines initiate and sustain the perpetuation of processes leading to chronic inflammatory conditions such as inflammatory bowel diseases (IBD). The nature of the trigger causing an inflammatory reaction decides whether type 1, type 17, or type 2 immune responses, typically characterized by the respective T- helper cell subsets, come into effect. In the intestine, Type 2 responses have been linked with mucosal healing and resolution upon an immune challenge involving parasitic infections. However, type 2 cytokines are frequently elevated in certain types of IBD in particular ulcerative colitis (UC) leading to the assumption that Th2 cells might critically support the pathogenesis of UC raising the question of whether such elevated type 2 responses in IBD are beneficial or detrimental. In line with this, previous studies showed that suppression of IL-13 and other type 2 related molecules in murine models could improve the outcomes of intestinal inflammation. However, therapeutic attempts of neutralizing IL-13 in ulcerative colitis patients have yielded no benefits. Thus, a better understanding of the role of type 2 cytokines in regulating intestinal inflammation is required. Here, we took a comparative transcriptomic approach to address how Th2 responses evolve in different mouse models of colitis and human IBD datasets. Our data show that type 2 immune-related transcripts are induced in the inflamed gut of IBD patients in both Crohn's disease and UC and across widely used mouse models of IBD. Collectively our data implicate that the presence of a type 2 signature rather defines a distinct state of intestinal inflammation than a disease-specific pathomechanism.

Identification of a Long Noncoding RNA TRAF3IP2-AS1 as Key Regulator of IL-17 Signaling through the SRSF10-IRF1-Act1 Axis in Autoimmune Diseases

IL-17A plays an essential role in the pathogenesis of many autoimmune diseases, including psoriasis and multiple sclerosis. Act1 is a critical adaptor in the IL-17A signaling pathway. In this study, we report that an anti-sense long noncoding RNA, TRAF3IP2-AS1, regulates Act1 expression and IL-17A signaling by recruiting SRSF10, which downregulates the expression of IRF1, a transcriptional factor of Act1. Interestingly, we found that a psoriasis-susceptible variant of TRAF3IP2-AS1 A4165G (rs13210247) is a gain-of-function mutant. Furthermore, we identified a mouse gene E130307A14-Rik that is homologous to TRAF3IP2-AS1 and has a similar ability to regulate Act1 expression and IL-17A signaling. Importantly, treatment with lentiviruses expressing E130307A14-Rik or SRSF10 yielded therapeutic effects in mouse models of psoriasis and experimental autoimmune encephalomyelitis. These findings suggest that TRAF3IP2-AS1 and/or SRSF10 may represent attractive therapeutic targets in the treatment of IL-17-related autoimmune diseases, such as psoriasis and multiple sclerosis.

Regulation of smooth muscle contraction by monomeric non-RhoA GTPases

Smooth muscle contraction in the cardiovascular system, airways, prostate and lower urinary tract is involved in the pathophysiology of many diseases, including cardiovascular and obstructive lung disease plus lower urinary tract symptoms, which are associated with high prevalence of morbidity and mortality. This prominent clinical role of smooth muscle tone has led to the molecular mechanisms involved being subjected to extensive research. In general smooth muscle contraction is promoted by three major signalling pathways, including the monomeric GTPase RhoA pathway. However, emerging evidence suggests that monomeric GTPases other than RhoA may be involved in signal transduction in smooth muscle contraction, including Rac GTPases, cell division control protein 42 homologue, adenosine ribosylation factor 6, Ras, Rap1b and Rab GTPases. Here, we review these emerging functions of non-RhoA GTPases in smooth muscle contraction, which has now become increasingly more evident and constitutes an emerging and innovative research area of high clinical relevance.

Homoharringtonine Inhibits Allergic Inflammations by Regulating NF-κB-miR-183-5p-BTG1 Axis

Homoharringtonine (HHT) is a drug for treatment of chronic myeloid leukemia. However, the role of HHT in allergic inflammations remains unknown. Mouse model of atopic dermatitis (AD) induced by 2, 4,-dinitroflurobenzene (DNFB) and anaphylaxis employing 2,4-dinitropheny-human serum albumin (DNP-HSA) were used to examine the role of HHT in allergic inflammations. HHT inhibited in vitro allergic reactions and attenuated clinical symptoms associated with AD. DNFB induced features of allergic reactions in rat basophilic leukemia (RBL2H3) cells. HHT suppressed effect of AD on the expression of Th1/Th2 cytokines. HHT inhibited passive cutaneous anaphylaxis and passive systemic anaphylaxis. MiR-183-5p, increased by antigen stimulation, was downregulated by HHT in RBL2H3 cells. MiR-183-5p inhibitor suppressed anaphylaxis and AD. B cell translocation gene 1 (BTG1) was shown to be a direct target of miR-183-5p. BTG1 prevented antigen from inducing molecular features of in vitro allergic reactions. AD increased the expression of NF-κB, and NF-κB showed binding to the promoter sequences of miR-183-5p. NF-κB and miR-183 formed positive feedback to mediate in vitro allergic reactions. Thus, HHT can be an anti-allergy drug. We present evidence that NF-κB-miR-183-5p-BTG1 axis can serve as target for development of anti-allergy drug.

Targeting IL-17A/glucocorticoid synergy to CSF3 expression in neutrophilic airway diseases

IL-17A plays a critical role in the pathogenesis of steroid-resistant neutrophilic airway inflammation, which is a hallmark of severe asthma and chronic obstructive pulmonary disease (COPD). Through RNA sequencing analysis of transcriptomes of human airway smooth muscle cells treated with IL-17A, dexamethasone (DEX, a synthetic glucocorticoid drug), alone or in combination, we identified a group of genes that are synergistically induced by IL-17A and DEX, including the neutrophil-promoting cytokine CSF3. In type-17 (Th17/IL-17Ahi) preclinical models of neutrophilic severe asthma (acute and chronic) and COPD, although DEX treatment was able to reduce the expression of neutrophil-mobilizing CXCL1 and CXCL2 in lung tissue, CSF3 expression was upregulated by DEX treatment. We found that DEX treatment alone failed to alleviate neutrophilic airway inflammation and pathology, and even exacerbated the disease phenotype when CSF3 was highly induced. Disruption of the IL-17A/DEX synergy by IL-17A inhibition with anti-IL-17A mAb or cyanidin-3-glucoside (C3G, a small-molecule IL-17A blocker) or depletion of CSF3 effectively rendered DEX sensitivity in type-17 preclinical models of neutrophilic airway diseases. Our study elucidates what we believe is a novel mechanism of steroid resistance in type-17 neutrophilic airway inflammation and offers an effective steroid-sparing therapeutic strategy (combined low-dose DEX and C3G) for treating neutrophilic airway diseases.